<template>
    <!-- 图形验证码 -->
    <div class="s-canvas">
        <canvas id="s-canvas" :width="contentWidth" :height="contentHeight"></canvas>
    </div>
</template>
<script>
export default {
    name: 'SIdentify',
    props: {
        identifyCode: {
            type: String,
            default: '1234'
        },
        fontSizeMin: {
            type: Number,
            default: 35
        },
        fontSizeMax: {
            type: Number,
            default: 35
        },
        backgroundColorMin: {
            type: Number,
            default: 180
        },
        backgroundColorMax: {
            type: Number,
            default: 240
        },
        colorMin: {
            type: Number,
            default: 50
        },
      colorMax: {
        type: Number,
        default: 160
      },
      lineColorMin: {
        type: Number,
        default: 100
      },
      lineColorMax: {
        type: Number,
        default: 200
      },
      dotColorMin: {
        type: Number,
        default: 0
      },
      dotColorMax: {
        type: Number,
        default: 255
      },
      contentWidth: {
        type: Number,
        default: 120
      },
      contentHeight: {
        type: Number,
        default: 40
    }
    },
    watch: {
        identifyCode() {
            this.drawPic()
        }
    },
    mounted() {
        this.drawPic()
    },
    methods: {
      // 生成一个随机数
        randomNum(min, max) {
            return Math.floor(Math.random() * (max - min) + min)
        },
      // 生成一个随机的颜色
    randomColor(min, max) {
        let r = this.randomNum(min, max)
        let g = this.randomNum(min, max)
        let b = this.randomNum(min, max)
        return 'rgb(' + r + ',' + g + ',' + b + ')'
    },
    transparent() {
        return 'rgb(255,255,255)'
    },
    drawPic() {
        let canvas = document.getElementById('s-canvas')
        let ctx = canvas.getContext('2d')
        ctx.textBaseline = 'bottom'
        // 绘制背景
        ctx.fillStyle = this.randomColor(this.backgroundColorMin, this.backgroundColorMax)
        ctx.fillStyle = this.transparent()
        ctx.fillRect(0, 0, this.contentWidth, this.contentHeight)
        // 绘制文字
        for (let i = 0; i < this.identifyCode.length; i++) {
            this.drawText(ctx, this.identifyCode[i], i)
        }
        // 绘制背景
        this.drawLine(ctx)
        this.drawDot(ctx)
    },
    drawText(ctx, txt, i) {
        ctx.fillStyle = this.randomColor(this.colorMin, this.colorMax)
        ctx.font = this.randomNum(this.fontSizeMin, this.fontSizeMax) + 'px SimHei'
        let x = (i + 1) * (this.contentWidth / (this.identifyCode.length + 1))
        let y = this.randomNum(this.fontSizeMax, this.contentHeight - 5)
        var deg = this.randomNum(-10, 10)
        // 修改坐标原点和旋转角度
        ctx.translate(x, y)
        ctx.rotate((deg * Math.PI) / 180)
        ctx.fillText(txt, 0, 0)
        // 恢复坐标原点和旋转角度
        ctx.rotate((-deg * Math.PI) / 180)
        ctx.translate(-x, -y)
    },
    drawLine(ctx) {
        // 绘制干扰线
        for (let i = 0; i < 8; i++) {
        ctx.strokeStyle = this.randomColor(this.lineColorMin, this.lineColorMax)
        ctx.beginPath()
        ctx.moveTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight))
        ctx.lineTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight))
        ctx.stroke()
    }
    },
    drawDot(ctx) {
        // 绘制干扰点
        for (let i = 0; i < 100; i++) {
            ctx.fillStyle = this.randomColor(0, 255)
            ctx.beginPath()
            ctx.arc(
                this.randomNum(0, this.contentWidth),
                this.randomNum(0, this.contentHeight),
                1,
                0,
                2 * Math.PI
            )
            ctx.fill()
            }
        }
    }
}
</script>

